JPH07148430A - New catalyst containing metal oxide and gas treat-ing method using said catalyst - Google Patents

Abstract

PURPOSE: To obtain a catalyst for the conversion of carbon sulfide and hydrogen cyanide in the presence of oxygen in a standard concentration and below by using a molybdenum promoted titania catalyst containing a mixture of cobalt and nickel. CONSTITUTION: This catalyst contains about 0.5-5.0 wt.% metal oxide selected from cobalt oxide, nickel oxide and a mixture of these, about 1.5-15 wt.% molybdenum trioxide and about 70-98 wt.% titanium dioxide. When a gas stream containing carbon sulfide and/or HCN is brought into contact with the catalyst, sulfur contained as carbon sulfide and/or nitrogen contained as HCN are converted to H2 S and NH3 , respectively, even in the presence of oxygen in <=2 vol.%, preferably <=1 vol.% concentration.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel catalyst and a method for converting carbon sulfide and hydrogen cyanide using the catalyst.

[0002]

Gases containing sulfur compounds and / or hydrogen cyanide are often generated in the industry using combustion furnaces.
For example, the tail gas stream from a furnace carbon black manufacturing process typically contains carbon sulfides such as carbon disulfide (CS ₂ ) and carbonyl sulfide (COS), and also hydrogen cyanide (HCN).

Act on Release of Sulfur-Containing Species into the Atmosphere
And sulfur regulations to remove sulfur-containing species from the gas stream.
It is often desirable to leave. CS₂And COS are ratio
It has a relatively inert chemistry that allows it to be removed from the gas stream.
It may be difficult to leave. On the other hand, hydrogen sulfide (H
₂S) is easily removed from the gas stream by various methods
It Sulfur as carbon sulfide is catalytically converted to H₂To S
Converted; similarly, nitrogen as HCN is catalytically
To react with ammonia (NH₃)become. These rolls
Typical commercial catalysts for oxidation are titania
Tungsten), cobalt and molybdenum promoted alumina (co-oxide
Baltic and molybdenum trioxide / aluminum oxide), bearing
There are body-plated platinum and chromium oxide promoted alumina. these
Typical commercial catalysts are effective in the absence of oxygen.
It However, the low concentration (about 0.1% or more) in the supply gas
Even in the presence of oxygen, these substances are desirable for their
Loss of catalytic function. For example, in the presence of oxygen,
moted) Alumina catalysts are sulphated and lose catalytic activity. Chi
For tania catalysts, a low concentration of oxygen causes sulfur species to ₂
And / or COS, and carbon sulfide and HCN
May result in inadequate conversion of

To overcome the adverse effects of oxygen on the typically used catalysts, two-stage catalyst beds have been proposed. For example, U.S. Pat. No. 4,981,661 discloses a two-stage process in which oxygen is removed by hydrogenation in the first stage and catalytic hydration of carbon sulfide and HCN in the second stage. Decomposition occurs. However, it is believed that it would be advantageous to have a catalyst that is effective in the conversion of carbon sulfide and HCN even in the presence of oxygen and therefore can be used in a one-step catalytic reactor.

[0005]

It is an object of the present invention to provide a new catalyst. This catalyst is present in the presence of oxygen at a concentration of 2% by volume or less (dry basis), preferably in the presence of oxygen at a concentration of 1% by volume or less (dry basis).
It is particularly effective in converting carbon sulfide and HCN. Another object of the invention is a process for converting carbon sulphide and HCN in a gas stream using the catalyst of the invention.

[0006]

We have developed novel cobalt and molybdenum promoted titania catalysts, nickel and molybdenum promoted titania catalysts, and molybdenum promoted titania catalysts containing a mixture of cobalt and nickel. This catalyst is particularly effective for use in the conversion of carbon sulfide and HCN even in the presence of oxygen at a concentration of 2% by volume or less (dry basis). This catalyst has the following components: Cobalt oxide (C
oO) or nickel oxide (NiO), or a mixture thereof, about 0.5 to about 5.0 wt%; molybdenum trioxide (MoO ₃ ) about 1.5 to about 15 wt%; titanium dioxide (TiO _2). ) About 70 to about 98% by weight. Preferably, the catalyst comprises from about 2.0 to about 3.5% of CoO or NiO, and MoO ₃ of about 8 to about 12%. In fact, the minimum required loading of CoO or NiO and MoO ₃ depends on the concentration of oxygen in the gas to be treated; the higher the oxygen concentration, the higher the required proportion of CoO or NiO and MoO ₃ . The catalyst can take any shape known in the art. The catalyst can be prepared by any method known in the art, for example by impregnating titania pellets with an aqueous solution of a salt of a promoter metal.

The process of the present invention comprises contacting the catalyst of the present invention with a gas stream containing carbon sulfide and / or HCN to add sulfur contained as carbon sulfide and / or nitrogen contained as HCN to H ₂ S and NH, respectively. Including conversion to ₃ and.
The gas may contain up to 2% by volume (dry basis) of oxygen. The gas stream must also contain sufficient steam and / or hydrogen (H ₂ ) to catalytically convert carbon sulfide and / or HCN.

The catalyst of the present invention advantageously promotes the conversion of sulfur present as carbon sulphide into hydrogen sulphide and / or the conversion of nitrogen present as HCN into ammonia, whereby carbon sulphide and HCN in the gas stream are present. And reduce the level with. The catalyst of the present invention and the method of the present invention are particularly advantageous for use in catalyzing the conversion of carbon sulfide and HCN components of a gas stream produced by a furnace carbon black reactor in the production of carbon black. . Further details and advantages of the catalyst and process of the present invention are as follows:
A more detailed description of the invention is provided.

As mentioned above, the present invention relates to cobalt and molybdenum promoted titania catalysts, or nickel and molybdenum promoted titania catalysts, and molybdenum promoted titania catalysts containing a mixture of cobalt and nickel. The invention also relates to a process for converting sulfur as carbon sulphide and / or nitrogen present as hydrogen cyanide into hydrogen sulphide and ammonia, respectively, using a catalyst. The catalyst of the present invention comprises the following components: cobalt oxide (CoO) or nickel oxide (NiO), or about 0.5 to about 5.0% by weight of a mixture thereof; molybdenum trioxide (MoO ₃ ) about 1.5 to about. About 15% by weight; titanium dioxide (TiO ₂ )
About 70 to about 98% by weight. Preferably, the catalyst is about 2.0 to about 3.5% CoO or NiO and about 8.
0 to about 12.0% MoO ₃ . In fact, CoO
Alternatively, the minimum required level of NiO and MoO ₃ depends on the concentration of oxygen in the feed gas. The catalyst can take any shape known in the art.

The catalyst of the present invention can be prepared by any method known in the art. For example, the catalyst of the present invention is Co
Alternatively, it can be produced by impregnating titania pellets with an aqueous solution of Ni and Mo promoter metal salts. A sufficient amount of the promoter metal salt to produce the desired concentration of the promoter metal oxide in the catalyst is dissolved in the required amount of water which corresponds approximately to the titania absorption capacity. Allow the titania to absorb the salt solution, and slowly add the salt solution to the titania. Solutions of each of the Mo and Co or Ni promoter metal salts can be added separately and continuously to the titania, or the metal salt solutions can be combined and added to the titania. The impregnated titania is then dried. After drying,
The catalyst of the present invention is produced by calcining a promoter metal containing a titania carrier in flowing air while gradually increasing the temperature. The method of making the catalyst of the present invention is described in further detail in Example 1 below.

The process of the present invention comprises contacting a catalyst of the present invention with a gas stream containing at least one component selected from the group consisting of carbon sulfide (eg, CS ₂ and COS) and HCN. The gas stream then provides sufficient levels of water vapor and / or hydrogen to convert sulfur as carbon sulfide (eg CS ₂ and COS) to H ₂ S and / or nitrogen present as HCN to NH ₃ . Including. The gas stream may contain up to 2% by volume (dry basis) of oxygen.

More specifically, according to the method of the present invention,
The following components: cobalt oxide (CoO), nickel oxide (NiO), or a mixture thereof in an amount of about 0.5 to about 5.0% by weight; molybdenum trioxide (MoO ₃ ) about 1.5 to about 15% by weight. A gas flow to a cobalt and molybdenum promoted titania catalyst, or a nickel and molybdenum promoted titania catalyst, or a molybdenum promoted titania catalyst comprising a mixture of cobalt and nickel, comprising about 70 to about 98 wt% titanium dioxide (TiO ₂ ). Contact. Preferably, the catalyst comprises from about 2.0 to about 3.5 wt% of CoO or NiO, and MoO ₃ of about 8 to about 12 wt%.

The process of the present invention can be carried out in a single stage catalytic reactor containing the catalyst of the present invention. The design and size of this single-stage catalytic reactor is within the knowledge of one of ordinary skill in the art and depends on the nature of the gas stream containing the carbon sulfide and / or HCN components to be converted. When carrying out this method, a gas stream containing carbon sulfide and / or HCN is fed through a tube or similar means into the catalytic reactor to contact the catalyst. The residence time and temperature in the catalytic reactor must be sufficient to ensure the desired conversion of carbon sulfide and HCN. Water can be introduced into the gas stream upstream of or in the catalytic reactor if the gas stream does not contain sufficient steam or hydrogen to carry out this conversion. Further details regarding the catalysts and methods of the present invention, as well as the advantages of the catalysts and methods of the present invention, will be apparent from the examples below.

A vacuum generator MM8- was used to determine the composition of most of the gas streams described in the examples below.
An 805 process mass spectrometer was used. Prior to introducing it into the mass spectrometer, the gas stream was directed through Permapur Products (P
erma Pure Products Incorporated (Toms River, NJ) was used to dry to about 2 wt% moisture.
The concentration of water in the gas stream depends on the composition (formulation) and the residual species (s).
pecies balance). The feed gas compositions of Examples 3 and 5 were calculated from the feed gas compositions of Examples 2 and 4, respectively, and the air addition rate used to introduce oxygen into the feed gas.

[0015]

EXAMPLE 1 This example illustrates the preparation of the catalyst of the present invention. The cobalt and molybdenum promoted titania catalysts of the present invention were prepared by the following procedure. La Roche Chemicals
Laroche S701 titanium dioxide (commercially available titania) sold by Micals) (Baton Rouge, LA) was used as the catalyst support. At first,
The initial process of titania
pient wetness) was measured. i. The paper towel was saturated with water and placed in a beaker. 3 pieces of titania (length about 1 cm, total weight about 0.7
0 g) was placed on top of a damp paper towel in a beaker. ii. The titania pieces were left on a saturated towel until the water was absorbed by the titania pieces and the surface of the titania became wet (about 2 hours). iii. Next, titania pieces were weighed to measure the amount of water absorbed per weight of titania. Perform initial wetness test 3 times,
Average water absorption per weight of titania (average initial wet point)
Was 0.43 g water / g titania.

Next, the titania carrier was impregnated with a solution containing cobalt and molybdenum. The final catalyst was intended to contain 3.3% by weight CoO and 10% by weight MoO ₃ .
It was calculated that 75 g of titania carrier absorb about 32 ml of water. Therefore, 11.1 g of cobalt nitrate hexahydrate and 10.5 g of ammonium molybdate tetrahydrate were added to water 3 times.
A solution containing cobalt and molybdenum was prepared by dissolving in 2 ml. The amount of cobalt nitrate and ammonium molybdenum trioxide used in the production of the solution was determined to be 3.3% by weight of CoO and M by chemical analysis using a metal salt reagent.
Co required for the preparation of the final catalyst containing 10% by weight of oO _3.
Was determined by calculating the amounts of Mo and Mo.

This solution containing cobalt and molybdenum was gradually added to 75 g of titanium support in the form of pellets less than about 1/2 cm in diameter. The solution was added in a manner that allowed for sufficient time for all of the solution to be absorbed by the titania pores.

The moist impregnated titanium was then spread on a tray and allowed to dry overnight at room temperature,
Calcination by heating in flowing air. Calcination temperature from about 200 ° F (93.3 ° C) to 900 as follows
The molybdenum-promoted titania catalyst of the present invention was produced by gradually increasing the temperature to ° F (482.2 ° C): temperature, holding time at temperature 200 ° F (93.3 ° C) 4 hours, 300 ° F (148.9 ° C) ) 4 hours 600 ° F (315.6 ° C) 4 hours 900 ° F (482.2 ° C) 4 hours

Example 2 This example illustrates the use of the catalyst of Example 1 in the process of the present invention. 47 cm ³ of the catalyst of the present invention prepared in Example 1 was placed in a 2.8 cm diameter vertical quartz tube reactor. The reactor was sealed, coupled to a source of feed gas, and a gas stream was introduced into the reactor, through the catalyst bed, and out the opposite end of the reactor. The temperature of the feed gas and the catalyst bed is 45
Maintain at 0 ° F (232.2 ° C) and feed gas rate to 36
00 hr ^-1 was controlled at a gas hourly space velocity (GHSV).

The composition of the gas stream entering and leaving the reactor was measured according to the procedure described herein. The results are shown in Table 1 below:

[Table 1] Table 1 Gas flow composition

The results are shown graphically in FIG. During 0.0-0.4 hours, FIG. 1 shows the composition of the reactor feed gas. Only at 0.4 hours does the feed gas pass through the catalyst bed and the reactor effluent concentrations of CS ₂ , COS and HCN drop substantially compared to their concentration in the feed gas. The results shown in Table 1 and FIG. 1 demonstrate that the catalyst of Example 1 effectively catalyzed the conversion of CS ₂ , COS and HCN components in the feed gas. CS ₂ , C
The conversion rates of OS and HCN were calculated from the results in Table 1 and shown in Table 2 below.

[Table 2] These results show that the method and catalyst of the present invention produce CS ₂ , CO
It proves to be advantageous for use in converting S and HCN.

Example 3 This example illustrates that the catalyst of Example 1 and the method of the present invention are also effective in the presence of oxygen in the feed gas. The same catalyst and reactor feed as described in Example 2 were used. However, in this example, the feed gas is 0.32
% Oxygen.

The composition of the gas stream entering and leaving the reactor was measured according to the procedure described herein. The results are shown in Table 3 below:

[Table 3] Table 3 Gas flow composition

These results are also shown graphically in FIG.
You At 2.8 hours, 0.32% oxygen (0.
5%) was injected into the feed gas. Set of reactor effluent gas streams
No substantive changes in growth are observed. This catalyst is CS₂,
It effectively promoted the conversion of COS and HCN. Table 3
The results shown in FIG. 1 and FIG. 1 show that the catalyst of Example 1 is C in the feed gas.
S ₂, COS and HCN components conversion in the presence of oxygen
Even in this case, it will be proved that the promotion was effective. C
S₂, COS and HCN conversion rates calculated from the results in Table 3
The results are shown in Table 4 below.

[Table 4] These results show that the method of the present invention and the catalyst of Example 1
Even if oxygen is present in the gas stream, CS _{2 of} the gas stream,
It proves to be advantageous for use in converting COS and HCN components.

Example 4 This example illustrates the use of other catalysts of the invention in the process of the invention. This catalyst is NiO 2.5% and Mo
It contained 9.0% O ₃ and the balance (balance) titania (La Roche S701). This catalyst was prepared by the impregnation method described in Example 1, but in this case nickel nitrate hexahydrate was used in place of cobalt nitrate hexahydrate,
The amount of metal salt used is NiO (2.5% by weight) and MoO.
_It was adjusted to give the desired loading of ₃ (9.0% by weight). 47 cm ³ of this catalyst was placed in a vertical quartz tube reactor having a diameter of 2.8 cm. The reactor was sealed, coupled to a source of feed gas, and a gas stream was introduced into the reactor, through the catalyst bed, and out the opposite end of the reactor. The temperature of the feed gas and catalyst bed was maintained at 450 ° F (232.2 ° C) and the feed gas velocity was controlled to be 3600 h ^-1 gas hourly space velocity (GHSV).

The composition of the gas stream entering and leaving the reactor was measured according to the procedure described herein. The results are shown in Table 5 below:

[Table 5] Table 5 Gas flow composition

The results are shown graphically in FIG. During the 0.0 to 0.35 hour period, FIG. 2 shows the composition of the reactor feed gas. Only after 0.35 hours the feed gas has passed through the catalyst bed and the reactor effluent gas concentrations of CS ₂ , COS and HCN have dropped substantially compared to their concentrations in the feed gas. The results, shown in Table 5 and FIG. 2, demonstrate that the catalyst of this example effectively catalyzed the conversion of CS ₂ , COS and HCN components in the feed gas. CS
The conversion rates of ₂ , COS and HCN were calculated from the results of Table 5 and shown in Table 6 below.

[Table 6] These results, catalyst and the method and the CS _2, CO of the present invention
It proves to be advantageous for use in converting S and HCN.

Example 5 This example illustrates that the catalyst of Example 4 and the method of the present invention are also effective in the presence of oxygen in the feed gas. The same catalyst and reactor feed as described in Example 4 were used. However, in this example, the feed gas is 0.32
% Oxygen.

The composition of the gas stream entering and leaving the reactor was measured according to the procedure described herein. The results are shown in Table 7 below:

[Table 7] Table 7 Gas flow composition

These results are also shown graphically in FIG. Oxygen 0.32% at 3.4 hours (0.
5%) was injected into the feed gas. No substantial change in the composition of the reactor effluent gas stream is observed. The results shown in Table 7 and FIG. 2 show that the catalyst of this example was used for the CS ₂ , C in the feed gas stream.
It is demonstrated that the conversion of OS and HCN components was effectively promoted even in the presence of oxygen. CS ₂ , CO
The conversion rates of S and HCN were calculated from the results in Table 7 and shown in Table 8 below.

[Table 8] These results indicate that the method of the present invention and the catalyst of this example have a CS in the gas stream even when oxygen is present in the gas stream.
₂ , demonstrated to be advantageous for use in converting COS and HCN components. It will be clearly understood that the forms of the invention described herein are illustrative only and are not intended to limit the scope of the invention.

[Brief description of drawings]

FIG. 1 CoO—Mo of the present invention as described in Examples 2 and 3.
CS ₂ , COS and HC with O ₃ -promoted titania catalyst
Graph of conversion of N.

FIG. 2 NiO—Mo of the present invention as described in Examples 4 and 5.
CS ₂ , COS and HC with O ₃ -promoted titania catalyst
Graph of conversion of N.

Claims (12)

[Claims] 1. An amount in the range of about 0.5 to about 5.0% by weight.
Cobalt oxide (CoO), nickel oxide (NiO)
Or a metal oxide selected from the group consisting of mixtures thereof
And tritium oxide in an amount ranging from about 1.5 to about 15% by weight.
Buden (MoO ₃) And; in the range of about 70 to about 98% by weight.
Amount of titanium dioxide (TiO 2₂) And a catalyst containing. 2. The catalyst according to claim 1, wherein the metal oxide is cobalt oxide (CoO). 3. The catalyst according to claim 1, wherein the metal oxide is nickel oxide (NiO). 4. The metal oxide is about 2.0 to about 3.5% by weight.
The catalyst of claim 1, wherein the molybdenum trioxide (MoO ₃ ) is present in an amount ranging from 8.0 to 12.0 wt%. 5. The metal oxide is cobalt oxide (CoO) present in an amount of about 3.3% by weight and molybdenum trioxide (MoO ₃ ) is present in an amount of about 10.0% by weight, The catalyst of claim 1 wherein titanium dioxide is present in an amount of about 86.7% by weight. 6. The metal oxide is nickel oxide (NiO), present in an amount of about 2.5% by weight, and molybdenum trioxide (MoO ₃ ) is present in an amount of about 9.0% by weight, The catalyst of claim 1 wherein titanium dioxide is present in an amount of about 88.5% by weight. 7. A gas stream containing at least one component selected from the group consisting of carbon sulfide and hydrogen cyanide is about 0.
Cobalt oxide (Co) in an amount ranging from 5 to about 5.0% by weight.
O), nickel oxide (NiO) or a metal oxide selected from the group consisting of a mixture thereof; about 1.5 to about 15
Molybdenum trioxide (MoO ₃ ) in an amount in the range of weight percent;
Titanium dioxide (Ti) in an amount ranging from about 70 to about 98% by weight.
O ₂ ) and a catalyst comprising a gas stream in which the gas stream converts sulfur as carbon sulfide to hydrogen sulfide and nitrogen as hydrogen cyanide in sufficient amount to convert ammonia to ammonia and / or hydrogen. The method comprising: 8. The metal oxide is about 2.0 to about 3.5% by weight.
The method of claim 7 present in an amount ranging from molybdenum trioxide (MoO ₃₎ is present in an amount of from about 8.0 to about 12.0 wt%. 9. The method of claim 7, wherein the carbon sulfide is selected from the group consisting of carbon disulfide (CS ₂ ) and carbonyl sulfide (COS). 10. The method of claim 7, wherein the gas stream further comprises up to 2.0% by volume of oxygen (dry basis). 11. The method according to claim 7, wherein the gas stream further comprises up to 1.0% by volume (dry basis) of oxygen. 12. The method of claim 7, wherein the gas stream comprises water vapor and hydrogen.